The Usage Logging database can only store and display information via defined views to only a maximum of 31 days.
The following PowerShell command error validates my statement:
Set-SPUsageDefinition : Cannot validate argument on parameter
'DaysRetained'. The 32 argument is greater than the maximum allowed
range of 31. Supply an argum ent that is less than 31 and then try the
command again.
Set-SPUsageDefinition -Identity <SPUsageDefinitionPipeBind> [-Enable] [-DaysRetained <0-31>] [-Verbose]
Get-SPUsageDefinition
will list the definition Names with their current retention periods.